Thanks for the replies
looks like I really have to take out those boards. I used a mirror to see what's on the other side and saw that if even they look okay from down below, it looks like a jungle topside.
Once those boards are down, it'll be easier to access and observe those pipes...will have to lock down the upper restroom to avoid any additional moisture from seeping in while this area is being dried/repaired.
Just noticed that it is just some 2x2 wood beams holding those boards in place. What other material can I use aside from those? I'm afraid those things have been contaminated by rot/spores already and might give way soon also.
would encasing those pipes in concrete or polyurethane after thoroughly sealing them be a good idea?